System for increasing horizontal field of view of a camera

Abstract

A terrestrial imaging device includes an objective lens which accepts light within an intrinsic angular field of view onto a focal plane and two pairs of plane mirrors. The first pair of plane mirrors reflects a first light incoming ray sequentially to produce first and second reflected light rays within a roughly horizontal plane, the second reflected ray being focused by the objective lens on the focal plane. The second pair of plane mirrors reflects a second incoming ray sequentially to produce third and fourth reflected light rays within a roughly vertical plane, the fourth reflected light ray being focused by the objective lens on the focal plane.

1. A system comprising:
 (a) a terrestrial imaging device including an objective lens which accepts light within an intrinsic angular field of view onto a focal plane, wherein the center of said focal plane and the center of said objective lens form an optical axis; 
 (b) a first pair of plane mirrors including a first mirror and a second mirror; wherein said first mirror reflects a first light ray emanating from a terrestrial scene, thereby producing a first reflected light ray, wherein said first reflected light ray is second reflected by said second mirror, thereby producing a second reflected light ray which is focused by the objective on the focal plane, wherein said first reflected light ray and said second reflected light ray form a first plane of reflection, wherein said first plane of reflection is substantially horizontal and wherein the angle between said first light ray and said optical axis is substantially greater than half of said intrinsic angular field of view; and 
 (c) a second pair of plane mirrors including a third mirror and a fourth mirror, wherein said third mirror reflects a second light ray emanating from a terrestrial scene, thereby producing a third reflected light ray, wherein said third reflected light ray is reflected by said fourth mirror, thereby forming a fourth reflected light ray which is focused by the objective on the focal plane, wherein said third reflected light ray and said fourth reflected light ray form a second plane of reflection, wherein said second plane of reflection is substantially vertical and wherein the angle between said second light ray and said optical axis is less than or equal to half of said intrinsic angular field of view; 
 wherein said first pair and said second pair of plane mirrors are substantially disposed vertically on opposite sides of said optical axis. 
 
   
   
     2. The system of  claim 1 , wherein said first pair of mirrors images a first image portion on said focal plane and said second pair of mirrors images a second image portion on said focal plane, wherein the horizontal angular field of view accepted to form both image portions is greater than said intrinsic angular field of view and wherein the vertical angular field of view accepted to form both image portions is less than said intrinsic angular field of view. 
   
   
     3. The system of  claim 2 , wherein the horizontal angular field of view is up to twice said intrinsic angular field of view. 
   
   
     4. The system of  claim 2 , wherein the vertical angular field of view is not less than half said intrinsic angular field of view. 
   
   
     5. The system of  claim 1 , wherein said first pair and said second pair of mirrors are assembled together with said terrestrial imaging device during manufacture of the system. 
   
   
     6. The system of  claim 1 , wherein said first pair and said second pair of mirrors are retrofit subsequent to assembly of said terrestrial imaging device. 
   
   
     7. The system of  claim 1 , wherein said terrestrial imaging device is selected from the group consisting of: an infrared camera, and a visible light camera, and binoculars. 
   
   
     8. The system of  claim 1 , wherein said intrinsic angular field of view is greater than ten degrees.